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Biomedical subjects

A Baker

Publications and source records attributed to A Baker.

At least 199 records · Page 11Linked to original sources
PubMed1989

Two genes encode the adenine nucleotide translocator of maize mitochondria. Isolation, characterisation and expression of the structural genes.

Southern blot hybridisation of maize (Zea mays) genomic DNA with a specific cDNA probe and sequence analysis of several cDNAs have revealed that the mitochondrial adenine nucleotide translocator (ADP/ATP carrier) is encoded by two genes, both of which are expressed in dark-grown coleoptile tissue. The structural genes (designated ANT-G1 and ANT-G2), encoding the two translocator polypeptides, have been isolated from a maize genomic library and characterised by DNA sequence analysis, mung bean nuclease mapping and primer extension. The two genes each contain two introns and encode very similar proteins. Transcripts from both genes have long (approximately 200 nucleotides) 5' untranslated leaders which are unusual in that they contain several ATG codons upstream of the initiation codon. Transcript analysis of RNA extracted from serial sections of developing maize leaves reveals that the translocator genes are most actively transcribed in the basal meristem, while transcripts were undetectable in green leaves.

Amino Acid Sequence↗
PubMed1989

MESOL--management education syllabus and open learning.

The NHS must develop its own managers and the biggest task, and one which cannot be postponed, is the development of many thousands of in-service personnel such as department heads. Last year the NHSTA announced the launching of MESOL, which is designed to this end. Alison Baker describes the thinking behind this ambitious programme.

Administrative Personnel↗
PubMed1988

Reduced activities of thiamine-dependent enzymes in the brains and peripheral tissues of patients with Alzheimer's disease.

A report of cell loss in the nucleus basalis of Meynert in patients with Wernicke-Korsakoff disease prompted the examination of thiamine pyrophosphate (TPP)-dependent enzymes in the brain and peripheral tissues of patients with Alzheimer's disease. In these brains, the activities of the 2-ketoglutarate dehydrogenase complex were reduced more than 75% and those of transketolase more than 45%. Decreases occurred in histologically damaged and in relatively undamaged areas. Small but statistically significant abnormalities of transketolase, but not of 2-ketoglutarate dehydrogenase complex, were identified in red blood cells and cultured fibroblasts. Previous studies have shown deficiencies in the brain and variable effects in peripheral tissues on another TPP-dependent enzyme--the pyruvate dehydrogenase complex. Activities of TPP-dependent enzymes appear to be deficient in the brain and perhaps in some peripheral tissues in patients with Alzheimer's disease.

Aged↗
PubMed1988

Transport of proteins into yeast mitochondria.

The amino-terminal sequences of several imported mitochondrial precursor proteins have been shown to contain all the information required for transport to and sorting within mitochondria. Proteins transported into the matrix contain a matrix-targeting sequence. Proteins destined for other submitochondrial compartments contain, in addition, an intramitochondrial sorting sequence. The sorting sequence in the cytochrome c1 presequence is a stop-transport sequence for the inner mitochondrial membrane. Proteins containing cleavable presequences can reach the intermembrane space by either of two pathways: (1) Part of the presequence is transported into the matrix; the attached protein, however, is transported across the outer but not the inner membrane (eg, the cytochrome c1 presequence). (2) The precursor is first transported into the matrix; part of the presequence is then removed, and the protein is reexported across the inner membrane (eg, the precursor of the iron-sulphur protein of the cytochrome bc1 complex). Matrix-targeting sequences lack primary amino acid sequence homology, but they share structural characteristics. Many DNA sequences in a genome can potentially encode a matrix-targeting sequence. These sequences become active if positioned upstream of a protein coding sequence. Artificial matrix-targeting sequences include synthetic presequences consisting of only a few different amino acids, a known amphiphilic helix found inside a cytosolic protein, and the presequence of an imported chloroplast protein. Transport of proteins across mitochrondrial membranes requires a membrane potential, ATP, and a 45-kd protein of the mitochondrial outer membrane. The ATP requirement for import is correlated with a stable structure in the imported precursor molecule. We suggest that transmembrane transport of a stably folded precursor requires an ATP-dependent unfolding of the precursor protein.

Biological Transport↗
PubMed1988

Anal cancer in women.

We studied predisposing factors in 56 women with anal cancer, comparing them with 56 matched controls drawn from the population. A detailed pretested questionnaire was administered to each study subject in a structured interview and blood was drawn for detection of herpes simplex virus antibodies by radioimmunoassay. Pathologic material from cases was obtained and evidence of human papilloma virus infection was sought. By univariate analyses we found associations between anal cancer and positive herpes simplex virus 2 titer (p = 0.0017), cigarette smoking (p = 0.0028), previous positive or questionable cervical Papanicolaou smear (p = 0.0124), and increasing number of sexual partners (p = 0.0224). By the multivariate technique of logistic regression there were independent and significant associations with cigarette smoking (p = 0.0126), previous use of hemorrhoid preparations (p = 0.0149), and history of disturbed bowel habits for greater than 1 mo (p = 0.0273). Anal cancer in women is a rare disease associated with cigarette smoking and sexual experience. Its association with previous anorectal disease is unclear and deserving of further study.

Adult↗
PubMed1988

A specific ELISA method for determining chloroquine in urine or dried blood spots.

Reported is an enzyme-linked immunosorbent assay (ELISA) that has been optimized and validated for the determination of chloroquine in urine or dried blood spots. The assay employs antisera raised in sheep to a chloroquine derivative conjugated to keyhole limpet haemocyanin and chloroquine conjugated to porcine thyroglobulin adsorbed onto the wells of a microtitration plate. The competitive binding of the antiserum to the wells was monitored using an alkaline-phosphatase-conjugated second antibody and a specific substrate. The assay exhibits no cross-reactivity with known chloroquine metabolites, other antimalarials, and commonly used drugs. The method was used to determine chloroquine in dried blood spot extracts and urine from a patient who was receiving a prescribed prophylactic chloroquine regimen. The drug was detected in the urine for 17 weeks and in the dried blood spots for 4 weeks after termination of the therapy.

Adult↗
PubMed1987

Sequences from a prokaryotic genome or the mouse dihydrofolate reductase gene can restore the import of a truncated precursor protein into yeast mitochondria.

Sequences that are capable of restoring mitochondrial targeting to a truncated yeast cytochrome c oxidase subunit IV presequence are encoded within the genome of Escherichia coli and within the gene for a higher eukaryotic cytosolic protein, mouse dihydrofolate reductase. These sequences, which resemble authentic presequences in their overall amino acid composition and degree of hydrophobicity, are rather frequent; greater than 2.7% of clones generated from E. coli DNA and greater than 5% of clones from the dihydrofolate reductase gene were functional in our screening system. These results suggest that, during evolution, mitochondrial precursor proteins could arise as a result of DNA rearrangements that place potential mitochondrial presequences at the amino terminus of existing open reading frames. Primitive eukaryotic cells may have used this mechanism to target proteins to their endosymbiotic protomitochondria.

Amino Acid Sequence↗
PubMed1986

Sequence and expression of human estrogen receptor complementary DNA.

The mechanism by which the estrogen receptor and other steroid hormone receptors regulate gene expression in eukaryotic cells is not well understood. In this study, a complementary DNA clone containing the entire translated portion of the messenger RNA for the estrogen receptor from MCF-7 human breast cancer cells was sequenced and then expressed in Chinese hamster ovary (CHO-K1) cells to give a functional protein. An open reading frame of 1785 nucleotides in the complementary DNA corresponded to a polypeptide of 595 amino acids and a molecular weight of 66,200, which is in good agreement with published molecular weight values of 65,000 to 70,000 for the estrogen receptor. Homogenates of transformed Chinese hamster ovary cells containing a protein that bound [3H]estradiol and sedimented as a 4S complex in salt-containing sucrose gradients and as an 8 to 9S complex in the absence of salt. Interaction of this receptor-[3H]estradiol complex with a monoclonal antibody that is specific for primate ER confirms the identity of the expressed complementary DNA as human estrogen receptor. Amino acid sequence comparisons revealed significant regional homology among the human estrogen receptor, the human glucocorticoid receptor, and the putative v-erbA oncogene product. This suggests that steroid receptor genes and the avian erythroblastosis viral oncogene are derived from a common primordial gene. The homologous region, which is rich in cysteine, lysine, and arginine, may represent the DNA-binding domain of these proteins.

Amino Acid Sequence↗
PubMed1986

The availability of insurance to long-time survivors of childhood cancer.

The authors identified 100 adults who survived cancer who were diagnosed and treated in childhood between 1945 and 1975. Using standardized interviews, each survivor and matched same-sex sibling was asked about life and health including questions about insurance. Compared with their same-sex siblings, childhood cancer survivors had significantly more difficulty in securing life insurance (P less than 0.001), in having life insurance in force (P less than 0.004), and in obtaining health insurance because of health reasons (P less than 0.001). Survivors were significantly less likely than siblings to be covered by health insurance (P less than 0.04). Cure of childhood cancer has become more common, allowing thousands of survivors to enter adult life. This study suggests that childhood cancer survivors have an unmet need in respect to life and health insurance.

Adolescent↗
PubMed1986

Childhood Menetrier's disease: four new cases and discussion of the literature.

Four cases of childhood Menetrier's disease are presented and their clinical and laboratory findings are compared with the other childhood cases reported in the literature. Children with Menetrier's disease usually present with abdominal pain or nausea and vomiting associated with peripheral edema, ascites, or pleural effusion; these symptoms are due to gastrointestinal protein loss and resultant hypoproteinemia. There is no evidence of urinary protein loss. The favorable clinical course as well as distinctive laboratory and roentgenologic findings distinguish this entity from other causes of these symptoms. Supportive therapy is normally all that is required since the symptoms resolve spontaneously in weeks to months. Surgery may be needed in rare cases of active gastrointestinal hemorrhage.

Child↗
PubMed1986

Two concurrent epidemics of enteroviral meningitis in an obstetric neonatal unit.

A small epidemic of viral infection occurred in a neonatal unit. It involved 11 infants, all of whom recovered. Echovirus 11 was the cause of illness in six infants, coxsackie B3 in four, and one infant had a biphasic illness, due first to echo 11, then to coxsackie B3. The epidemic coincided with a major outbreak of echovirus 11 and a smaller outbreak of coxsackie B3 in the community. Several staff became ill. Five infants were considered to have been infected by perinatal materno-infant spread, others by cross-infection. The epidemic ended when the nursery was closed.

Australia↗
PubMed1985

Isolation and sequence analysis of a cDNA encoding the ATP/ADP translocator of Zea mays L.

A cDNA complementary to the mRNA for the ATP/ADP translocator of maize (Zea mays L.) has been identified by virtue of hybridisation with the homologous gene from yeast. The cloned cDNA has been shown by DNA sequence analysis to contain an open reading frame of 954bp., which encodes a polypeptide of molecular weight 40,519. This polypeptide exhibits a high degree of homology to the translocator polypeptides of beef heart and Neurospora crassa mitochondria.

Amino Acid Sequence↗
PubMed1985

A randomized, prospective trial of adjuvant chemotherapy in adults with soft tissue sarcomas of the head and neck, breast, and trunk.

Since 1977, 31 patients were entered in a randomized, prospective study testing the efficacy of adjuvant chemotherapy after aggressive local treatment of high-grade sarcomas of the head, neck, breast, and trunk (excluding retroperitoneal sarcomas). All patients had complete resection of gross tumor and underwent postoperative radiotherapy (6000-6300 rads over 7-8 weeks). Seventeen patients received adjuvant chemotherapy consisting of doxorubicin (less than or equal to 550 mg/m2), cyclophosphamide (less than or equal to 5500 mg/m2), and methotrexate (less than or equal to 1000 mg/kg). Three-year actuarial disease-free survival in the chemotherapy arm was 77%, compared to 49% in the no-chemotherapy arm (P = 0.075). Three-year overall actuarial survivals in the two treatment arms, however, were 68% and 58%, respectively (P = 0.38). Considering only patients with tumors of the trunk (22 patients), 3-year actuarial disease-free survival in the chemotherapy arm was 92%, compared to 47% in the no-chemotherapy arm (P = 0.006). Actuarial 3-year overall survival in the chemotherapy arm was 82%, compared to 61% in the no-chemotherapy arm (P = 0.18). An additional 26 patients were treated in an identical fashion, but were not part of the randomized trial because of contraindications to chemotherapy, refusal to enter the randomized trial, or because they were treated before 1977 in a trial in which all patients received chemotherapy. Considering the entire group of 57 patients, follow-up ranged from 10 to 86 months (median, 35 months). Local control was achieved in 46 patients (81%); 3-year actuarial disease-free and overall survivals were 67% and 77%, respectively. A tendency toward improved disease-free survival was apparent among patients treated with chemotherapy (P = 0.018), but there was no statistically significant improvement in overall actuarial survival (P = 0.46). The subgroup of patients with sarcomas of the trunk (39 patients) demonstrated the greatest benefit from chemotherapy, with regard to disease-free survival (P less than or equal to 0.001). The most significant toxicity associated with chemotherapy was doxorubicin-induced cardiomyopathy, which resulted in clinically apparent congestive heart failure in five patients. Thus, the use of chemotherapy when combined with aggressive local measures appears to improve disease-free survival, but additional patients and longer follow-up are necessary to determine if improved overall survival will result.

Actuarial Analysis↗
PubMed1985

Differential effects of monovalent, divalent and trivalent metal ions on rat brain hexokinase.

The effects of monovalent (Li+, Cs+) divalent (Cu2+, Ca2+, Sr2+, Ba2+, Zn2+, Cd2+, Hg2+, Pb2+, Mn2+, Fe2+, Co2+, Ni2+) and trivalent (Cr3+, Fe3+, Al3+) metals ions on hexokinase activity in rat brain cytosol were compared at 500 microM. The rank order of their potency as inhibitors of brain hexokinase was: Cr3+ (IC50 = 1.3 microM) greater than Hg2+ = Al3+ greater than Cu2+ greater than Pb2+ (IC50 = 80 microM) greater than Fe3+ (IC50 = 250 microM) greater than Cd2+ (IC50 = 540 microM) greater than Zn2+ (IC50 = 560 microM). However, at 500 microM Co2+ slightly stimulated brain hexokinase whereas the other metal ions were without effect. That inhibition of brain glucose metabolism may be an important mechanism in the neurotoxicity of metals is suggested.

Animals↗
PubMed1985

Results of multimodality therapy of resectable soft-tissue sarcomas of the retroperitoneum.

Thirty-seven patients with resectable retroperitoneal sarcomas were studied prospectively to determine the efficacy of aggressive multimodality treatments. No patients was lost to follow-up, which ranged from 11 to 85 months (median 29 months). All patients received radiotherapy and some received postoperative chemotherapy (doxorubicin, cyclophosphamide, and high-dose methotrexate). A subset of 15 patients were entered into a prospective, randomized study testing the efficacy of adjuvant chemotherapy (eight received chemotherapy; seven did not). Two-year actuarial survival rates were inferior in the chemotherapy arm (100% versus 47%; p = 0.06), but the small number of patients precluded drawing definitive conclusions from this randomized study alone. Among the entire 37 patients (21 received chemotherapy; 16 did not) the actuarial 3-year survival rate was 43% and appeared unaffected by chemotherapy. Two patients suffered doxorubicin infiltration, three sustained cardiac toxicity, two developed cyclophosphamide-induced cystitis, and three withstood transient, severe bone marrow suppression. Eight patients suffered severe radiation enteritis, and one patient died after bowel resection for this problem. Thus the chemotherapy regimen we administered did not appear to improve survival but was associated with major morbidity. Radiotherapy was also associated with major complications, and since all patients received radiotherapy, it remains to be established if this modality is beneficial in improving survival.

Actuarial Analysis↗
PubMed1984

Late occurrence of malignancy in a ganglioneuroma 19 years following radiation therapy to a neuroblastoma.

Neuroblastoma is a common solid tumor of childhood. Maturation to a ganglioneuroma or regression has been reported to occur spontaneously or following minimal treatment. Malignant degeneration of such a ganglioneuroma is extremely rare. We present a report of a malignant tumor arising in a ganglioneuroma 19 years following abdominal radiation therapy for neuroblastoma.

Abdominal Neoplasms↗